Safety-crank for internal-combustion engines.



N0.892,049. PATENTED JUNE 30, 1908. N. W. HARTMAN.

SAFETY CRANK FOR INTERNAL COMBUSTION ENGINES.

APPLICATION FILED SEPT.3,1907.

9 2. mi 168.988; Im/e mfon UNITED STATES" PATENT OFFICE.

' v NOBLE 7W. alar OF T OLEDOi onro. i i

v SAFETY-CRANK FOR INTERNAL-COMBUISTION ENGINES.

No.- 892,049. a 1

Specification of Letters Patent.

Patented June 30,

Application filed September 3, 1907. Serial No. 391,001.

To all whom "it may. concern:

.Be it known thatl, NOB E W. I'IARTMAN, a citizen of the United States, residing at T oledo, in the county of Lucas and State of Ohio, have invented certain new and useful Improvements in Safety-Cranks forInternal-. Combustion Engines; and I doideclare the following to be a full ,,,clear, and exact de scription of the invention; such-as'will enable others skilled in the art to which it appertains to'make andusethe same, reference being had to' the aecompanying drawings, and to the letters and figures of reference marked thereon, which form a part of this specification My invention relates to a safety crank for starting internal combustion engines suchas are commonly used in automobiles and launches, and its object is to. provide a device which shall overcome the dangers attending the use ofthcse cranks as commonly constructed and the frequent mishaps which occur when premature explosions or back firing take place in the cylinder of the engine and the crank is thrown back against thev hands or arms of the operator.

A further object of my invention is to furnish a device of the described character which may be readily applied to the starting cranks of any of these engines now commonly in use.

I attain these objects by means of the devices and arrangement of parts hereinafter described and shown, and illustrated in the accompanying drawings in which,-

Figure 1 is a front-elevation of my device with the crank removed; Fig. 2 a sideeleva tion showing the crank in place with the frame and escutcheon hereinafter referred to, in section; Fig. 3, a top-plan view of the same showing the engine shaft in section, and Fig. 4, a rear-elevation of the crank detached.

Like numerals of reference indicate like parts throughout the drawings.

In the drawings, 1 is a crank-arm, 2 the handle, and 3 the hub of the crank. Upon the hub is an enlarged disk-like portion 4 havin teeth or cogs 5 upon its periphery arranged spirally to the axis of the hub.

6 represents a portion of the frame of an automobile having thercthrough an opening. 7 adapted for-the reception of the extremity of the crank hub.

8 is an escutcheon or ring resting against the outer face of the frame and surrounding the disk-like part 4 of the hub. Rigidly secured to the escutcheon' are two inwardly projecting pins 9 passing through holes 10 in the frame and provided. at their inner extrcmltics with heads ll. lictwcen hold the cscutcheon S normally against the escutcheon to be moved laterally outwanlly away from the frame. 13-43 are pins which project radially inwardly through the escutclwon or ring 5' and. which are rigidly secured in place, forming internal teeth in the ring. their inner ends are adapted to engage the spiral teeth 5 on the hub. 14 is the engine-shaft which is engaged wit h crated forwardly by the lunul-crank and so that when the shaft is revolved rapidly ahead by the engine the crank will be disengaged. from the shaft. in the present instance, for illustration, the end of the crank-shaft is bored axially, as at .15, to receive a reduced portion 16 on the inner end of the crank-huh. Through this reduced portion passes a pin 17 the projecting ends of which are adapted to engage radial shoulders 18 formed upon the end of the crank-shaft at opposite sides of the bore 15. When the reduced portion of the crank-shaft is inserted into the bore 15, the pins 17 engage the shoulders 18 and the crank and the shaft may now be rotated forwardly together. \Vhen the engine starts rapidly ahead, the crank is forced outwardly and out of engagement with the crank-shaft by means of the wedgedike action of the beveled portions 19 on the end of the crank-shaft. Ordinarily if the crank-shaft revolves backcarries the pin 17- with it, causing the crankarm and handle to deliver a violent blow to anything in their path.

The operation of my device is as follows: Upon the crank being turned in the proper direction the shaft turns with the crank in the usual manner and as above described. Now the pins 13 projecting into the S)lI{tl teeth 5 are, by the screw-like action of the teeth, caused to move outwardly away from the frame 10 of the machine, the springs 12 yielding to the outward movement of the escutcheon S and the pins 9. l/Vhilc the crank is goin in the proper direction the pins 13 slip idly along the outer ends of the teeth or cogs 5. It will be seen that the heads and the fran P. and surroululiug (heplns 9 are interposed spiral springs 12, which these i outer face of the frame but which permit the These pins at the crank-hub in the usual way, or-iulprc-- ferred manner, so that the shaft may lmfopwardly instead of forwardly, the shoulder 18 frame of the machine, instantly pulling spiral teeth now tendto hold the crank in engagement with the en ine shaft while thecrank is turned forward% with the necessity at such time of manu pressing inwardly on the crank, But should a back-fire takeplace the pins 13 in? stantly engage the spiral teeth 5 and travel in the opposite direction carrying the escu'tch-' eonor ring 8 iaterall toward and against the frame of the niac ine. Now, since the pins 13 cannot move inwardly more than, say, a quarter of an inch, the screw-like ac,- tion of the pins upon the spiral teeth forces the crank-hub outwardly and away from the crank out of operative engagement wit engine-shaft, Thus no harm results from the reverse movement of the engine-shaft.

Having described my invention, what I claim and desire to secure by Letters Patent, is-

1. In a device ofthe described character,

an engine-shaft, a hand-crank, means for operatively engaging the crank and shaft for forward rotation, and means forthe disengagement of the crank and shaft by th re: Q verse rotation of the shaft, said'latter means thus dispensing the the comprising a spirally toothed portion on the hub of the crank, a ring surroundingsaid spirall ternal teeth on the ring-aria ted for engagement wlthsaid spiral 'teet and.,a spring which holds said; internal teeth and said toothed portion, supports for the allyring which permit its lateral-movement, in-

which engage the s iral teeth of the hub,"

guide 5 pins upon t e ring which project through the frame-member, and springs which engage said guide-pins and said framemember and which hold the internal projections upon the rim normally engaged with the spiral teeth of t e crank-hub.

In testimony whereof I aflix my'signature in presence of two witnesses.

NOBLE W. HARTMAN.

Witnessesi CLEM' V. WAGNER, ADA E. CAMERON. 

